Project Summary/Abstract My interest in diseases of the nervous system stems from my undergraduate education at the University of Pennsylvania, where as a Wistar Institute undergraduate fellow with Dr. Art McMorris, I investigated extrinsic cues triggering cAMP signaling in glia. As an undergraduate research fellow at Rockefeller University in Dr. Bruce McEwen's laboratory, I investigated how hypothyroidism altered signaling molecules in the brain. These experiences led me to graduate school at Harvard University, where I trained with Dr. Azad Bonni in molecular neuroscience and elucidated signaling pathways that mediate survival and death signaling in mammalian neurons and in vivo in C. elegans. Upon completion of my PhD, I carried out my early postdoctocal training with Dr. Anna-Elina Lehesjoki at the Folkhlsan Institute of Genetics in Helsinki, Finland, where I discovered that impaired redox homeostasis is a key mechanism triggering neurodegeneration in the progresive myoclonus epilepsy, Unverricht-Lundborg disease (EPM1). From these research experiences, I have gained experience in molecular neuroscience and its applications to neurologic disease. I joined Dr. Chris Walsh's lab for my second postdoc, in hopes that comprehensive training in developmental neurobiology during the mentored phase of this award would complement my training in molecular neuroscience, and provide unique perspective on the mechanisms underlying neurologic disease throughout life. Dr. Walsh's is a leader in the field of cerebral cortical development research. I will learn fundamental techniques in the lab, ranging from quantitative histological analyses to in utero electroporations. Dr. Walsh has assembled a highly talented group of scientists, which will continue to provide a unique source of support and inspiration in informal conversations and weekly lab meetings and journal clubs. The Walsh lab is located in the Division of Genetics, which also hosts joint weekly data talks with the Division of Neuroscience, to promote collaborative exchanges and assistance with technical and theoretical isues. This intellectually engaging environment will provide an excellent source of discussion and feedback during the mentored phase of the award. Importantly, the Division of Genetics is committed to supporting the transition of postdocs to independent research positions. To this end, I will attend a number of career training seminars and meetings geared at preparing me for launching my independent research career. The long-term goal of my research is to elucidate how the cerebrospinal fluid (CSF) functions as a signaling niche that coordinates a rich interaction of signaling factors, acting at long distances to regulate target cell behavior during health and disease. During cerebral cortical development, rapid changes in proliferating progenitor cells occur almost synchronously across vast areas of the neuroepithelium. The protracted location of neuroepithelial cilia in the CSF suggests a potential role for the CSF as a source of extrinsic signals guiding progenitor proliferation. Since the CSF turns over several times per day, the CSF-choroid-plexus system is ideally suited for triggering rapid and spatially synchronized changes in molecular signaling across large distances. My immediate research goal in this proposal is to investigate the role of embryonic CSF proteome in regulating cortical progenitor proliferation during development. The experiments in Aim1 will use heterochronic explants and cultured stem cells to test the ability of CSF to support the survival, growth, and proliferation of cortical progenitor cells. Since the CSF contains hundreds of proteins, I will then use biochemical and genetic approaches to examine how Igf2 (Insulin-like growth factor 2), a candidate factor identified in our preliminary mass spectrometry analyses, may be actively distributed by the CSF to influence progenitor proliferation (Aim 2). The mentored phase of the award (Aims 1&2) will help refine the experimental models, techniques, and professional skills needed to launch a successful, independent research program examining the mechanisms by which CSF-distributed factors influence target cells in health and disease. The fundamental techniques including neurosphere cultures, quantitative histological analyses, and in utero electroporations, all learned during Aims 1&2, wil prepare me for the experiments proposed in Aim 3, which will explore the roles and mechanisms by which other CSF-borne signaling factors, such as retinoic acid and Sonic hedgehog, are regulated by the CSF to act on target cells at the ventricular surface. By the end of this award period, my independent research laboratory wil have pioneered a new concept in developmental biology in which the CSF plays an active role in cerebral cortical development. The proposed experiments represent a solid foundation for future studies investigating changes in the CSF stem cell niche in aging and age-associated neurologic disease. Since the CSF is a surgically accessible medium in humans and mouse models, the proposed experiments will pave the way towards development of powerful diagnostic and therapeutic approaches.